test(nodes): destroy editor after use

[max-nextcloud]

Fixes errors during test runs such as https://github.com/nextcloud/text/actions/runs/15742170977/job/44369984600

Use vitests test.extend to make sure destroy is also called if the test fails.

We create editors without destroying them in a lot more tests. I briefly tried to fix that with a editorTest fixture everywhere - but it's just too much work right now. I've only seen these ones error out during tests. So let's fix them when they throw exceptions one by one...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.33%. Comparing base (cdcb338) to head (2837b26).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7316   +/-   ##
=======================================
  Coverage   52.32%   52.33%           
=======================================
  Files         482      482           
  Lines       42038    42038           
  Branches     1047     1049    +2     
=======================================
+ Hits        21998    22000    +2     
+ Misses      19937    19935    -2     
  Partials      103      103           

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